Erosion control blocks protect the underlying ground against erosion of the soil and maintain the terrain in a desired condition. Interlocking erosion control blocks are well adapted for protecting the ground, as such type of blocks are constructed with interlocking arms that extend from one or more sides of a block, and interlocking sockets formed in other sides of the block. When interlocked together, neighbor blocks cannot be laterally moved from each other, thereby allowing high water flows thereover without compromising the integrity of a mat of blocks.
An interlocking revetment block generally has at least four sides with at least one interlocking arm or an interlocking socket on each side. Often, the corners of the revetment block are formed at an angle so that overall the block has an octagonal shape. Such a revetment block is disclosed in U.S. Pat. No. 5,556,228 by Smith. As can be appreciated, if a mat of such type of revetment blocks were installed, then the perimeter or border would have exposed interlocking arms and unfilled interlocking sockets. The irregular edge of the mat with unused arms or sockets allows the border blocks to more easily break or allow cracks to form through the block.
Interlocking revetment blocks are also formed with one or more vertical holes formed therein, from the top surface to the bottom surface. The vertical holes allow vegetation to grow therein and help anchor the block to the ground. A revetment block that has five vegetation holes therein is disclosed in U.S. Pat. No. 8,123,435, also by Smith.
Revetment blocks are often installed in watershed areas where soil erosion is to be prevented. The watershed areas are in many instances located in areas controlled by local or federal governments, and the primary concern is the long term protection of such areas from the erosion of soil due to frequent high-volume flows of rainwater, and the like. Generally, the aesthetics of such an area is not a concern, as the prevention of erosion is the primary goal to be achieved.
Generally, large areas of revetment blocks are installed using a single type or style of block. The use of two different types of blocks is usually not an alternative that is available because two different types of blocks must be maintained either in inventory, or must be fabricated for the project. For example, if an area to be protected from erosion requires the borders to be linear and without unused interlocking arms or sockets, then different shaped blocks must be employed. The fabrication of different style interlocking blocks necessitates the use of different shape molds at the fabrication plant. Revetment blocks are typically fabricated with heavy duty steel molds that are repeatedly used, thus making such molds expensive. Moreover, if a different style revetment block is to be fabricated, this requires that the entire female mold and male press head be removed and replaced with a different mold and press head adapted for fabricating the different shape block. This results in more costly revetment block products.
From the foregoing, it can be seen that a need exists for a mat of interlocking revetment blocks where the perimeter thereof is linear and devoid of interlocking arms or sockets. Another need exists for a mat of interlocking revetment blocks that has a linear perimeter so that it easily abuts against a linear border of concrete, such as a paved road, sidewalk, etc. Yet another need exists for a mat of interlocking revetment blocks that has a linear border, so that such mat can be used as a roadway and the perimeter is less likely to deteriorate and more likely to remain intact, even with heavy equipment traffic running over the edges of the mat. A further need exists for an economical method of fabricating different style revetment blocks using a universal mold where various components can be fastened or removed from the male and female mold parts, without changing out the entire mold.